// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "net/dns/notify_watcher_mac.h"

#include <notify.h>

#include "base/logging.h"
#include "base/posix/eintr_wrapper.h"

namespace net {

NotifyWatcherMac::NotifyWatcherMac()
    : notify_fd_(-1)
    , notify_token_(-1)
{
}

NotifyWatcherMac::~NotifyWatcherMac()
{
    Cancel();
}

bool NotifyWatcherMac::Watch(const char* key, const CallbackType& callback)
{
    DCHECK(key);
    DCHECK(!callback.is_null());
    Cancel();
    uint32_t status = notify_register_file_descriptor(
        key, &notify_fd_, 0, &notify_token_);
    if (status != NOTIFY_STATUS_OK)
        return false;
    DCHECK_GE(notify_fd_, 0);
    if (!base::MessageLoopForIO::current()->WatchFileDescriptor(
            notify_fd_,
            true,
            base::MessageLoopForIO::WATCH_READ,
            &watcher_,
            this)) {
        Cancel();
        return false;
    }
    callback_ = callback;
    return true;
}

void NotifyWatcherMac::Cancel()
{
    if (notify_fd_ >= 0) {
        notify_cancel(notify_token_); // Also closes |notify_fd_|.
        notify_fd_ = -1;
        callback_.Reset();
        watcher_.StopWatchingFileDescriptor();
    }
}

void NotifyWatcherMac::OnFileCanReadWithoutBlocking(int fd)
{
    int token;
    int status = HANDLE_EINTR(read(notify_fd_, &token, sizeof(token)));
    if (status != sizeof(token)) {
        Cancel();
        callback_.Run(false);
        return;
    }
    // Ignoring |token| value to avoid possible endianness mismatch:
    // http://openradar.appspot.com/8821081
    callback_.Run(true);
}

} // namespace net
